LRRK2 and Parkinson disease: Safety, tolerability and target engagement of DNL201 has already been established in a phase I, randomized, double-blind, placebo-controlled study in healthy volunteers (Tolosa et al. 2020), as well as in a placebo-controlled, dose-ranging study in 29 PD patients, including subgroups with and without LRRK2 mutation (NCT03710707), according to a press release (Therapeutics 2020).